Source file: docs/models/hammer-strength-iso-lateral-bench-press.md · rendered from the repository
Hammer Strength Plate-Loaded Iso-Lateral Bench Press (IL-BP)
Status: Parametric – formula ready, inputs must be measured
Confidence of outputs: estimated · method: mechanical-model · built: 2026-10-17
Mechanism: lever arm model (plate load × lever ratio)
Model
F(θ) = SR(θ) + P·x_p(θ)/L_h (per arm, force perpendicular to the pivot→grip line)
Why no full numeric estimate: No official dimension drawing with pivot/horn/grip positions was found. Design patent US D321025 (Hammer Corp., 1991, "isolateral dumbbell press") only claims an ornamental design: its figures are not dimensioned and not to scale, so lengths cannot be read off it.
Inputs
| Symbol | Input | Value | Status | Uncertainty | Source (verbatim quote) |
|---|---|---|---|---|---|
| SR | Starting resistance per work-arm Note: 7 lb = 3.18 kg. ROM position at which Hammer defines SR is not stated, so SR(θ) at mid/end is unknown. How to measure: Crane scale at the grip, empty arm, start/mid/end. |
3.2 kg | ✅ sourced | ± 0.227 — rounding of "7 lb" | manufacturer_page: “7 lb (3.2 kg)” — Spec table row "Starting Resistance (per arm)" · retrieved 2026-10-17 |
| L_h | Pivot axis → centre of grip How to measure: Tape from the centre of the pivot bolt to the centre of the hand position (±3 mm). |
— | 📏 to measure (Maxime) | — | — |
| x_p(θ) | Horizontal distance pivot axis → plate horn axis, at start/mid/end How to measure: Plumb line (string + carabiner) hanging from the horn end, tape horizontally to below the pivot. Repeat at start/mid/end. |
— | 📏 to measure (Maxime) | — | — |
| θ | Arm angle at start/mid/end How to measure: Phone level on the arm tube. |
— | 📏 to measure (Maxime) | — | — |
| P | Plates added per arm (label) | — | ⚙️ user setting | — | — |
Not modelled (known unknowns)
- Bearing friction at the pivot
- Exact SR definition point
Validation by Maxime
Follow docs/protocole-mesure-fr.md. Geometry/ratio to measure: L_h, x_p(θ), θ. Once measured, the inputs are entered and the curve is computed with the same code (research/models/build_models.py).